1. Field of the Invention
The present invention relates to methods and systems for cooling electrical components in a downhole environment and, more particularly, to methods and systems utilizing a flow of drilling fluid to cool electrical components.
2. Background and Related Art
The goal of accessing data from a drill string has been expressed for more than half a century. As exploration and drilling technology has improved, this goal has become more important in the industry for successful oil, gas, and geothermal well exploration and production. For example, to take advantage of the several advances in the design of various tools and techniques for oil and gas exploration, it would be beneficial to have real time data such as temperature, pressure, inclination, salinity, etc. Several attempts have been made to devise a successful system for accessing such drill string data. However, due to the complexity, expense, and unreliability of such systems, many attempts to create such a system have failed to achieve significant commercial acceptance.
In numerous patents and pending patent applications issued to or filed by the present inventors, Hall et al. (“Hall”), the inventors have disclosed a downhole transmission system, or downhole network, that overcomes many of the problems and limitations of the prior art. In such a system, data is transmitted in real time along the drill string by way of network hardware integrated directly into the drill string. This network hardware enables high-speed communication between various tools and sensors located along the drill string with surface analysis, diagnostic, and control equipment.
The previously mentioned patents and pending patent applications thus solve many of the problems of the prior art by providing a reliable high-speed connection between downhole drilling components and the surface. Novel apparatus and methods are needed, however, to ensure that electrical components integral to such a downhole transmission system function properly and are not adversely affected by extreme operating parameters downhole.
Extreme temperatures downhole are of particular concern as such temperatures, which may exceed 150° C., cause a shorter performance life in electrical components, and may cause such components to fail completely. In addition, heat generated by the electrical components themselves may contribute to overheating and associated failure to function.
A downhole transmission system assumes proper functioning of electrical components. Failure of one or more electrical components integral to a downhole transmission system may cause inaccurate, delayed and/or failed information between the surface and a downhole tool, thereby compromising the reliability of the transmission system as well as the efficiency and success of the entire drilling operation.
Thermoelectric cooling devices comprising semiconductor-based electronic components that function as small solid state heat pumps are known in the art. Such devices, however, fail to adequately cool electrical components in a downhole environment since efficient use of such devices requires direct thermal transfer, a prospect generally thought to require unreasonable subjection of sensitive electrical components to other harmful effects downhole, such as extreme vibrations, impacts, abrasives, and pressures. Indeed, prior art systems that implement such thermoelectric devices, such as the system disclosed in U.S. Pat. No. 6,134,892 to Turner (“Turner”), allow certain thermoelectric transfer inefficiencies to ensure adequate protection of electrical components from other harmful effects. Specifically, Turner requires several heat transfer steps to achieve heat transfer across a plurality of protective materials and devices used to insulate electrical components from hostile effects downhole. With each heat transfer step, there is a commensurate reduction in cooling efficiency and increased risk of overheating and failure in electrical components.
Known cooling devices and systems also tend to interfere with a flow of drilling fluid through the drill string.
Accordingly, what is needed is an improved downhole thermoelectric cooling system that minimizes a number of heat transfer steps to maximize cooling efficiency. Further what is needed is an improved downhole thermoelectric cooling system capable of protecting electrical components from hostile effects downhole without compromising cooling efficiency. Also what is needed is an improved downhole thermoelectric cooling system that does not interfere with a flow of drilling fluid through a central borehole of a drill string.
Such methods and systems are disclosed and claimed herein.